EUCHLANID AS. 91 
Euchlanis dilatata : ¢ F Moxon, Trans. Linn. Soc. vol. xxiv. 1864, p. 459, with figs, 
Eckstein, Sieb. u. KGll. Zeits. xxxix. 1883, p. 385, fig. 33. 
” ” 
SP. CH. Lorica a broad oval; dorsal plate depressed in front, arched behind ; 
transverse section (through the highest point) a low circular segment; dorsal occipital 
edge with a broad gap, joined to the head by a membrane; hind dorsal edge notched ; 
ventral plate flat with a broad flange of oval outline; trophi with five teeth in each 
uncus. 
This species, like that which precedes and that which follows it, has no occipital 
notch in the dorsal plate, but has a broad gap (fig. 5a), which is only visible when the 
head is completely withdrawn. The edge of the gap is united to the head by a softer 
continuation of the lorica, which effectually obliterates the gap when the head is 
protruded. The lorica, though depressed, slopes upwards a little to a point not far 
from the top of a posterior notch in it, and then drops abruptly as if pinched in on 
either side of the notch. The ventral plate is nearly as wide as the dorsal, and a ventral 
view shows the edge of its flange running parallel to the edge of the dorsal plate just 
within it. A side view shows the two edges as two parallel lines near together, and 
drawn along the animal’s side from end toend. Ehrenberg says that there are no sete 
on the foot, but both Dr. Moxon and Herr Eckstein draw a pair of pedal set, and I 
have met with specimens bearing sete in no other respect differmg from those that 
lacked them. Dr. Cohn (loc. cit.) gives a full description of the male. It is a reduced 
copy of the female with a sperm-sac and penis taking the place of the alimentary canal 
and mastax, which as usual are entirely wanting, Dr. Cohn has seen the wand-like 
spermatozoa ‘“‘ swarming ”’ in the sperm-sac. 
Length. Female, 2;, male, ; inch. Habitat. Clear ponds and ditches: common. 
E. macrura, Ehrenberg. 
(Pl. XXIII. fig. 6.) 
Euchlanis macrura c > 9 Ehrenberg, Die Infus. 1838, p. 463, Taf. lviii. fig. 1. 
SP. CH. “ Closely resembling E. dilatata; lorica a narrower oval ; toes somewhat 
longer; trophi with seven teeth in each uncus ; a pair of recurved sete on the foot.” 
T have met with an Huchlanis, whose figure is given in fig. 6, which had all the 
above characteristics given by Ehrenberg, but I doubt whether H. macrura is a good 
species, as none of the corresponding characters seem constant in H. dilatata, except the 
number of teeth in each uncus; and, unfortunately, I found several specimens, of what 
I should otherwise have termed EZ. macrwra, with only five teeth in each uncus. 
Length. About 7; inch. Habitat. Clear ponds and ditches : not uncommon. 
KE. triquetra, Ehrenberg. 
(Pl. XXII. fig. 4.) 
Euchlanis triquetra . . Ehrenberg, Die Infus. 1838, p. 461, Taf. lvii. fig. 8. 
if “6 0 5 ° 7 Hudson, Mon. Micr. J. viii. 1872, p. 97, pl. xxviii. 
SP. CH. Lorica oval, with a high flat median plate at right-angles to the dorsal 
surface ; transverse section (through the highest point) triangular ; dorsal occipital 
edge notched ; hind dorsal edge notched ; ventral plate concave, and (with its flange) 
two-thirds of the width of the dorsal plate ; trophi with five teeth in each uncus. 
This most beautiful species is often to be found among the confervoid growth on the 
walls of old ponds. Its lorica rises in a high thin plate, and is not unlike a delicate glass 
dish-cover set over an inverted glass dish somewhat narrower than itself. The vertical 
plate, that thus rises like a crest from the dorsal surface, is very flexible and elastic, and 
can be easily bent aside by the compressorium without injury. The ventral plate is 
curved downwards all round its edge, so that the lateral furrow between the two plates is 
wide ; and, as shown in fig. 40, its flange stretches barely half-way across the base of 
